Using a sensitive assay for measuring BCR-ABL, my laboratory monitors residual disease burden in all Philadelphia chromosome positive adult and pediatric patients with CML. Working closely with clinicians in NHLBI and NCI, our assays play an important role in guiding investigators in the use donor lymphocyte infusions or protein kinase inhibitors to treat otherwise undetectable, early disease recurrence. [unreadable] [unreadable] An analogous RT-PCR assay for measuring WT1, a tumor product expressed by many myeloid and lymphoid leukemia cells, has been developed in this lab for use in monitoring changes in leukemic cell burden in patients enrolled in an experimental dendritic cell/WT1-peptide immunization protocol initiated by Dr. Alan Wayne and associates within the NCI. Patient accrual has just begun and initial results may be available in the coming year.